Xtensive.Orm.Reprocessing 7.1.2

Xtensive.Orm.Reprocessing

Summary

The extension provides API for reprocessible operations. The reprocessible operation should represent a separate block of logic, usually a delegate of a method and be transactional.

Prerequisites

DataObjects.Net 7.1.x (http://dataobjects.net)

Examples of usage

Examples #1. Simple reprocessible operation looks like this:

  Domain.Execute(session => {
    // Task logic
  });

Expample #2. Usage of built-in reprocessing strategies.

There are 3 strategies that can be used for task execution:

• HandleReprocessibleException strategy The strategy catches all reprocessible expections (deadlock and transaction serialization exceptions) and makes another attempt to execute the task
• HandleUniqueConstraintViolation strategy The same as previous one but also catches unique constraint violation exception
• NoReprocess strategy No reprocessing is provided

To indicate that a particular strategy should be used, use the following syntax:

  Domain.WithStrategy(new HandleReprocessExceptionStrategy())
    .Execute(session => {
      // Task logic
    });

Examples of how to configure extension

Following examples show different ways to configure extension in configuration files of various types.

Example #1 Confugure in App.config/Web.config

<configuration>
  <configSections>
    
    <section name="Xtensive.Orm.Reprocessing" 
      type="Xtensive.Orm.Reprocessing.Configuration.ConfigurationSection, Xtensive.Orm.Reprocessing" />
  </configSections>

  <Xtensive.Orm.Reprocessing 
    defaultTransactionOpenMode="New" 
    defaultExecuteStrategy="Xtensive.Orm.Reprocessing.HandleReprocessableExceptionStrategy, Xtensive.Orm.Reprocessing">
  </Xtensive.Orm.Reprocessing>
</configuration>

Such configuration is usually read with System.Configuration.ConfigurationManager. If project still supports such configurations then Reprocessing configuration will be read automatically when it needs to be read. Sometimes a work-around is needed to read such configuration, for more read Example #2 and Example #3

Example #2 Reading old-style configuration of an assembly in NET 5 and newer.

Due to new architecture without AppDomain (which among the other things was in charge of gathering configuration files of loaded assemblies as it would be one configuration file) System.Configuration.ConfigurationManager now reads only configuration file of actual executable, loaded assemblies' configuration files stay unreachable by default, though there is need to read some data from them. A great example is test projects which are usually get loaded by test runner executable, and the only configuration accessible in this case is test runner one.

Extra step is required to read configuration files in such cases. Thankfully, ConfigurationManager has methods to get access to assemblies' configuration files.

To get access to an assembly configuration file it should be opened explicitly by

  var configuration = ConfigurationManager.OpenExeConfiguration(typeof(SomeTypeInConfigOwnerAssembly).Assembly.Location);

The instance returned from OpenExeConfiguration provides access to sections of the assembly configuration. DataObjects.Net configurations (DomainConfiguration, ReprocessingConfiguration, etc.) have Load() methods that can recieve this instance. ReprocessingConfiguration can be read like so

  var configuration = ConfigurationManager.OpenExeConfiguration(typeof(SomeTypeInConfigOwnerAssembly).Assembly.Location);
  var reprocessingConfig = ReprocessingConfiguration.Load(configuration);

  // loaded configuration should be manually placed to
  domainConfiguration.ExtensionConfigurations.Set(reprocessingConfig);

The domainConfiguration.ExtensionConfigurations is a new unified place from which the extension will try to get its configuration instead of calling default parameterless Load() method, which has not a lot of sense now, though the method is kept as a second source for backwards compatibility.

For more convenience, DomainConfiguration extensions are provided, which make code more neater. For instance,

  var configuration = ConfigurationManager.OpenExeConfiguration(typeof(SomeTypeInConfigOwnerAssembly).Assembly.Location);

  // the extension hides getting configuration with ReprocessingConfiguration.Load(configuration)
  // and also putting it to ExtensionConfigurations collection.
  domainConfiguration.ConfigureReprocessingExtension(configuration);

Custom section names are also supported if for some reason default section name is not used.

Example #3 Reading old-style configuration of an assembly in a project that uses appsettings.json file.

If for some reason there is need to keep the old-style configuration then there is a work-around as well. Static configuration manager provides method OpenMappedExeConfiguration() which allows to get any *.config file as System.Configuration.Configuration instance. For example,

  ExeConfigurationFileMap configFileMap = new ExeConfigurationFileMap();
  configFileMap.ExeConfigFilename = "Orm.config"; //or other file name, the file should exist bin folder
  var configuration = System.Configuration.ConfigurationManager.OpenMappedExeConfiguration(configFileMap, ConfigurationUserLevel.None);

After that, as in previous example, the instance can be passed to Load method of ReprocessingConfiguration to read extension configuration and later put it to DomainConfiguration.ExtensionConfigurations

  var reprocessingConfiguration = ReprocessingConfiguration.Load(configuration);

  domainConfiguration.ExtensionConfigurations.Set(reprocessingConfiguration);

Extension usage will look like

  domainConfiguration.ConfigureReprocessingExtension(configuration);

Example #4 Configure using Microsoft.Extensions.Configuration API.

This API allows to have configurations in various forms including JSON and XML formats. Loading of such files may differ depending on .NET version, check Microsoft manuals for instructions.

Allowed JSON and XML configuration definition look like below

<configuration>
  <Xtensive.Orm.Reprocessing>
    <DefaultTransactionOpenMode>New</DefaultTransactionOpenMode>
    <DefaultExecuteStrategy>Xtensive.Orm.Reprocessing.HandleReprocessableExceptionStrategy, Xtensive.Orm.Reprocessing</DefaultExecuteStrategy>
  </Xtensive.Orm.Reprocessing>
</configuration>

{
  "Xtensive.Orm.Reprocessing": {
    "DefaultTransactionOpenMode" : "New",
    "DefaultExecuteStrategy" : "Xtensive.Orm.Reprocessing.HandleReprocessableExceptionStrategy, Xtensive.Orm.Reprocessing"
  }
}

The API has certain issues with Xml elements with attributes so it is recommended to use more up-to-date attributeless nodes. For JSON it is pretty clear, almost averyone knows its format.

ReprocessingConfiguration.Load method can accept different types of abstractions from the API, including

• Microsoft.Extensions.Configuration.IConfiguration;
• Microsoft.Extensions.Configuration.IConfigurationRoot;
• Microsoft.Extensions.Configuration.IConfigurationSection.

Loading of configuration may look like

  
  var app = builder.Build();

  //...

  // tries to load from default section "Xtensive.Orm.Reprocessing"
  var reprocessingConfig = ReprocessingConfiguration.Load(app.Configuration);

  domainConfiguration.ExtensionConfigurations.Set(reprocessingConfig);

or, with use of extension, like

  
  var app = builder.Build();

  //...

  // tries to load from default section "Xtensive.Orm.Reprocessing"
  // and put it into domainConfiguration.ExtensionConfigurations

  domainConfiguration.ConfigureReprocessingExtension(app.Configuration);

Example #5 Configure using Microsoft.Extensions.Configuration API from section with non-default name.

For configurations like

<configuration>
  <Orm.Reprocessing>
    <DefaultTransactionOpenMode>New</DefaultTransactionOpenMode>
    <DefaultExecuteStrategy>Xtensive.Orm.Reprocessing.HandleReprocessableExceptionStrategy, Xtensive.Orm.Reprocessing</DefaultExecuteStrategy>
  </Orm.Reprocessing>
</configuration>

{
  "Orm.Reprocessing": {
    "DefaultTransactionOpenMode" : "New",
    "DefaultExecuteStrategy" : "Xtensive.Orm.Reprocessing.HandleReprocessableExceptionStrategy, Xtensive.Orm.Reprocessing"
  }
}

Loading of configuration may look like

  
  var app = builder.Build();

  //...

  var reprocessingConfig = ReprocessingConfiguration.Load(app.Configuration, "Orm.Reprocessing");

  domainConfiguration.ExtensionConfigurations.Set(reprocessingConfig);

or, with use of extension, like

  
  var app = builder.Build();

  //...

  domainConfiguration.ConfigureReprocessingExtension(app.Configuration, "Orm.Reprocessing");

Example #6 Configure using Microsoft.Extensions.Configuration API from sub-section deeper in section tree.

If for some reason extension configuration should be moved deeper in section tree like something below

<configuration>
  <Orm.Extensions>
    <Xtensive.Orm.Reprocessing>
      <DefaultTransactionOpenMode>New</DefaultTransactionOpenMode>
      <DefaultExecuteStrategy>Xtensive.Orm.Reprocessing.HandleReprocessableExceptionStrategy, Xtensive.Orm.Reprocessing</DefaultExecuteStrategy>
    </Xtensive.Orm.Reprocessing>
  </Orm.Extensions>
</configuration>

or in JSON

{
  "Orm.Extensions": {
    "Xtensive.Orm.Reprocessing": {
      "DefaultTransactionOpenMode" : "New",
      "DefaultExecuteStrategy" : "Xtensive.Orm.Reprocessing.HandleReprocessableExceptionStrategy, Xtensive.Orm.Reprocessing"
    }
  }
}

Then section must be provided manually, code may look like

  
  var app = builder.Build();

  //...

  var configurationRoot = app.Configuration;
  var extensionsGroupSection = configurationRoot.GetSection("Orm.Extensions");
  var reprocessingSection = extensionsGroupSection.GetSection("Xtensive.Orm.Reprocessing");

  var reprocessingConfig = ReprocessingConfiguration.Load(reprocessingSection);

  domainConfiguration.ExtensionConfigurations.Set(reprocessingConfig);

or, with use of extension method, like

  
  var app = builder.Build();

  //...

  var configurationRoot = app.Configuration;
  var extensionsGroupSection = configurationRoot.GetSection("Orm.Extensions");
  var reprocessingSection = extensionsGroupSection.GetSection("Xtensive.Orm.Reprocessing");

  domainConfiguration.ConfigureReprocessingExtension(reprocessingSection);